Evolution of the vibrational behavior of a guitar soundboard along successive construction phases by means of the modal analysis technique

Abstract

The crucial piece of a craft guitar is the soundboard since it determines the quality of the sound given by the instrument. From the initial phase (the gross plate with no hole) until the last construction phase (the plate with the full structure) several stages are followed to modify the dynamic behavior of the structure and hence the acoustic response of the final guitar. The aim of this work is to analyze the effect of each modification on the vibrational response of the plate. With this in mind, an experimental modal analysis of all the construction phases has been performed in the low frequency range under free conditions. The response of the plate in each stage is defined by vibration patterns, resonance frequencies, quality factors, and admittance curves.

Air Cavity Modes in the Resonance Box of the Guitar: The Effect of the Sound Hole

“…This cavity corresponds to the soundboard analyzed in previous works [10,11]. As the sound hole's role cannot be easily simulated, a preliminary "nite element model was used in order to de"ne the boundary conditions.…”

An efficient numerical method for the resolution of the Kirchhoff‐Love dynamic plate equation

“…For the second-order approximation (P 2 ᮍ [b]), the degrees of freedom are associated to the vertices, the edges and the center of each triangle, so that the elementary cell for ᐂ h 2 contains 6 dof [ Fig. 4(b 5) and the semi-discretized problem is written as …”

“…It is reinforced by struts, which are pieces of hard wood glued on its internal face. These struts have a great influence on the shape of the structural modes of the soundboard and on the radiation efficiency of the guitar [5,6]. The soundboard is modeled with the dynamic Kirchhoff-Love plate equation for an inhomogeneous orthotropic material with free and fixed boundaries.…”

Numerical Simulation of a Guitar

“…The measurement of the eigenfrequencies and eigenmodes of the soundboard of a guitar has been the subject of an important number of experiments [30,41,35]. In the present study, the purpose was not to simulate a particular instrument.…”